In the Linux kernel 4.13 through 4.16.11, ext4_read_inline_data() in fs/ext4/inline.c performs a memcpy with an untrusted length value in certain circumstances involving a crafted filesystem that stores the system.data extended attribute value in a dedicated inode.
https://usn.ubuntu.com/3752-3/
https://usn.ubuntu.com/3752-2/
https://usn.ubuntu.com/3752-1/